Air Crews in Training

An upgraded simulator helps train Air Force Reserve
C-130 aircrews

By Kevin Miller

Kevin
Miller is a principal analyst in the Advanced Technologies Department of
SwRI's Training, Simulation and Performance Improvement Division. His
area of technical concentration is the development of real-time software
for simulator-based training devices.

Imagine an Air Force
flight crew on a critical mission to support troops. The pilot is responsible
for safe transport of the crew and cargo to the final destination. The takeoff,
flight and landing are smooth and successful.

Given the high
fidelity of present-day flight simulators, plus mandates to reduce training
costs, it’s quite possible that the majority of flight crew training may have
taken place in a simulator. Aircrew training and certification traditionally
have been conducted in aircraft, but it is increasingly being conducted in
simulators.

At Dobbins Air Reserve
Base (ARB), Georgia, the flight training unit incorporates classroom
instruction, simulator training events and actual aircraft flights to train and
certify aircrew for the C-130H2 transport aircraft. Until recently, the C-130H2
Weapon System Trainer was the only simulator available for pilot, copilot, and
flight engineer training and certification. It was in use up to 18 hours a day,
six days a week to handle the student load, and this congestion was considered a
bottleneck for aircrew training. The Air Force Reserve Command (AFRC) decided in
2003, to procure a second H2 simulator. Budget limitations and numerous studies
led to the development of a unique acquisition plan. The AFRC would contract
services to upgrade an existing simulator in lieu of developing a new device.

In August 2003, the
AFRC directed the Air Education and Training Command (AETC) at Randolph Air
Force Base to convert an uncertified C-130H3 Unit Level Trainer to a certified
Level-6 C-130H2 Flight Training Device (FTD). The conversion was a joint
development effort between the AETC, Southwest Research Institute (SwRI) and a
team of subcontractors under the direction of SwRI. The Institute was the prime
contractor and technical manager. The three-year, $5 million program recently
concluded with the delivery, installation and certification testing of the
device at Dobbins ARB.

A
challenge for flight simulators is the accurate simulation of take off
and landing maneuvers with various aircraft configurations, such as
weights, environmental conditions and equipment malfunctions.

Training Environment

Just as aircrew
members are certified in a simulator to operate a certain aircraft type, the
simulator itself must also be certified. Most commercial and government flight
simulators that are built to represent a specific cockpit configuration are
certified in accordance with Federal Aviation Administration (FAA) guidelines or
standards and are assigned a complexity, or “fidelity” level. Levels A (lowest)
to D (highest) are reserved for top-of-the-line airplane simulators containing a
full-size replica of the cockpit, an out-the-window visual system and a motion
cueing system. Simulators that lack visual or motion systems are classified as
Level 4 (lowest) through 7 (highest). Certification is a complicated,
time-consuming and costly process where simulators are tested and their
performance is compared with actual aircraft performance as recorded in an
instrumented aircraft.

The flight training
device is to be used for tasks that were previously taught in the weapon system
trainer: familiarize students with cockpit controls, practice checklist and
emergency procedures, and practice instrument flying including take-offs,
landings and in-flight navigation. To support training, the device’s simulated
cockpit contains a replica of a C-130H2 flight deck that includes a pilot
position, a copilot position and a flight engineer position. A fourth position
for the navigator was not replicated. With few exceptions, the controls and
instruments look, feel and operate like actual aircraft components. However,
unlike the weapon system trainer, the flight training device does not have an
out-the-window visual system, nor is the flight deck mounted on a motion base.

Three instructor
positions are located behind the student positions. The most valuable quality of
the flight training device, as with most flight simulators, is its ability to
save and restore the simulated conditions of the aircraft and its environment,
“freeze” the simulation, and insert malfunctions. None of these can be easily or
safely performed in the actual aircraft. The freeze capability allows an
instructor to interrupt the simulation to insert guidance or discuss an
operational error with the student. A simulation freeze, combined with the
capability to restore the simulation to an earlier flight condition, allows the
student to repeatedly practice a training event, such as landing with one engine
out, until the skill is mastered. More than 200 simulated malfunctions, ranging
from an engine fire to a faulty temperature gauge, can be inserted on the fly or
automatically at a predetermined time or under certain flight conditions.

The FTD student
training positions, pilot (forward left, occupied here by Maj. James
Grogan), copilot (forward, right, occupied by MSgt. Michael Macaleese),
and flight engineer (aft, center, seat not shown), are a replica of the
C-130 H2 model flight deck. The instructor station positions are located
aft of the student positions.

Conversion Approach

The approach used to
convert the existing trainer is similar to an automobile overhaul, but more
complicated. The instrument panels and wiring harnesses were removed and
refurbished, the computers and software were replaced, student seats were
reupholstered, and the device received a new paint job.

Replacing the computer
systems was the most complicated of the conversion tasks. It was bound by five
critical client requirements: 1) to reduce life-cycle costs (acquisition plus 10
years of maintenance), 2) to maximize reuse of government-owned instrument and
aerodynamic modeling software from the weapon system trainer, 3) to maximize use
of new computer systems based on commercial off-the-shelf personal computer
technologies, 4) to replicate the weapon system trainer instructor interface;
and 5) to remove all proprietary software and replace it with open-source
software.

Instrument,
Aerodynamic and Environment Models

A host computer serves
as the simulation master that executes the reused aircraft instrument and
aerodynamic models. Real-time infrastructure components control the execution of
each model and maintain a pool of shared variables that facilitate inter-model
and inter-computer communications. The input/output (I/O) application scans the
position of flight deck controls, such as switches or knobs, and passes the data
to the host computer instrument models. In turn, the models use the data to set
variables that are passed back to the I/O application to drive display
components such as lamps and gauges.

More complicated
instrumentation warranted independent computer systems to host the simulation
models. The Self Contained Navigation System (SCNS) was simulated using existing
models. The primary pilot interface is a multi-function display unit containing
a small monitor and a keyboard. In combination with the aircraft's autopilot
system, the SCNS can automatically "fly" a flight plan. The Electronic
Traffic Collision Avoidance System is also simulated by reused models. The pilot
interface is an LCD (liquid crystal display) monitor that displays information
about adjacent aircraft and provides navigation solutions and audio warnings to
avoid a collision.

A foundation of C-130
simulator certification is the testing of models that simulate the
hydraulic-driven flight controls: the push-pull column that controls aircraft
pitch, the column wheel that controls aircraft roll, the rudder pedals that
control aircraft yaw, the foot-operated brakes, and the hand-operated nose
steering wheel. Because of existing proprietary software, the control loading
models were rewritten to replicate the weapons system trainer performance. The
models drive electric motors that are coupled to each hand- or foot-operated
control. The result is a simulated control that has the look and feel of the
aircraft during all aspects of operation, including hydraulic malfunctions. To
certify that the feel is accurate, force versus position plots are generated for
each control and compared against the aircraft data.

The FTD
uses a network of nine computer systems to simulate the C-130 flight
deck environment and allow instructors to monitor and control the
simulation.

Sound System

As in an actual
aircraft, students wear audio headsets to converse with fellow crew members,
ground personnel and other aircrafts crew members. Rewritten communication
models hosted by the sound system simulate operation of the C-130 intercom and
radio equipment. A specific enhancement allows instructors to monitor
transmissions and to provide instruction and role-play, such as providing air
traffic control guidance. The sound system also hosts aural cue models that
simulate C-130 flight deck ambient noise generated by the four turboprop
engines, air turbulence and hydraulic pumps.

Instructor and Operator Stations

The graphical user
interface at the instructor operation station (IOS) enables instructors to
control and monitor the training environment. To start the student training
session, an instructor selects an initial set of conditions that places the
simulated aircraft in a predetermined location, such as on the parking ramp,
engines off and the ground cart power connected; or on the runway with engines
running, ready for takeoff. The latter initial condition set will be
incorporated after the aircrew has mastered the engine start and taxi checklist
procedures and has experienced numerous abnormal conditions associated with
those procedures.

To start the training
scenario, the instructor, acting as a traffic controller, uses a radio to direct
the pilot. After the pilot reads back the departure instructions and confirms
the aircraft is ready, the controller releases the aircraft for takeoff. If the
instructor does nothing to speed up flight time, it may take a few hours to
complete the flight plan and land at the destination airport. To reduce
non-productive flight time, the graphical user interface allows the instructor
to “drag and drop” the aircraft anywhere on the flight path map.

The FTD student and
instructor stations are housed in an air conditioned enclosure. External
equipment racks (left) house computers, power supplies and electronic
equipment.

Conclusion

The flight training
device received a conditional Level-6 certification in August 2006. Converting
an existing training device saved the Air Force a considerable amount of money.
To develop a brand new simulator would have cost approximately $12 million while
the costs to reconfigure and certify an existing trainer were only about $5
million. The primary goal, to reduce weapon system trainer workload and to
increase the potential number of H2 students trained at Dobbins ARB, has been
achieved.

A secondary goal of
the trainer conversion effort was to pave the way for other simulator upgrades.
Some aspects of the technical approach used to convert the unit level trainer
could be used to upgrade other C-130 simulators. It is only a matter of time
before spare parts for the weapon system trainer’s early 1990s vintage
minicomputer system become hard to find. Before that happens, work will begin to
replace the simulation computers and replace proprietary software components.

Acknowledgments
The author gratefully acknowledges the contributions of the SwRI
development team members Senior Research Technologist James Hancock,
Senior Engineering Technologist Les Hughes, Senior Research Engineer
Stephen Gray, Research Analyst Craig Fenrich, Research Analyst Theresa
Huth, and Senior Research Engineer Thomas Moore. He would also like to
acknowledge the contributions of SwRI subcontractors and staff at AETC
Randolph AFB, the Air Force Reserves at Dobbins ARB, and the Air Force
Det3 at Little Rock AFB.